Practical Research On Merging Unit Based On IEC61850

With the promotion of electronic transformer progressively, the digital interfacebetween electronic transformer and secondary protection、measurement、control equipmenthas gradually become a problem which is widespread concerned. To solve this problem,IEC60044-7/8standard proposed the concept of merging unit for the first time. As thestandard of digital substation, IEC61850standard accepted and deepened the concept ofmerging unit. By considering the merging unit as one of the devices of IEC61850`sprocess layer, the concept of merging unit is integrated into IEC61850system.This paper analyzes the background of merging unit based on IEC61850standardfirstly, and on this basis, explores the significance of this study. Then this papersummarizes the present research status in the domestic and abroad, and thus introduces thecontent of this study.Merging unit is one of the digital substation devices, so before doing the research ofmerging unit we must have a comprehensive understanding of IEC61850standard at first.Based on the explanation of the main concepts of IEC61850standard, this paper analyzesthe IEC61850-9-2standard`s description and requirements of merging unit. By comparingIEC60044-7/8、IEC61850-9-1and IEC61850-9-2/LE，this paper analyzes merging unitfrom concept to practical exhaustively, and then builds the model of merging unit based onIEC61850-9-2/LE.This paper proposes a hardware design based on ARM+FPGA combination. Thispaper designs the hardware circuit and analyzes the realization of specific functions ofmerging unit which depend on the specific actual hardware. Based on the division of thefunctions of merging unit, combining with actual hardware system, this paper compiles thecontrol system、Ethernet communication driver、time synchronization program、dataprocess program and data configuration program and etc..Finally, this paper tests the developed hardware circuit and application programrespectively. This paper also tests the comprehensive performance of merging unit andconfirming that the merging unit developed by this study can achieve the functions based on IEC61850-9-2/LE.